This invention relates to a rate sensor essential to space stabilization of the tracking assembly in a homing system.
Heretofore, various kinds of rate sensors have been developed for use in navigation systems and highly accurate guidance systems. Examples of such rate sensors include fiber optic gyros, laser ring gyros, and gyroscopes equipped with a gimbal mechanism. The rate integration gyros and dynamically tuned gyros (also known as "tuned dry gyros") are known types of gambal equipped gyroscopes. When such a rate sensor is applied to a navigation or highly accurate guidance system, it is required to stabilize the gimbals on which a housing antenna or optical system is mounted. The construction of the conventional guidance system is described in, for instance, "International Offense Review", p 118, published by the Interavia S.A. in 1976. This guidance system design is such that it is equipped with an IR homing head using a cassegrain system, a reticle and an infrared (IR) detector. The homing optical system (seeker) and a gyro are mounted on gimbals and the rotational directions of the rotary axis of the gimbals are controlled by feeding back the output of the rate sensor to a torquer to make the optical system follow the target position.
As shown in the above example, the centers of the seeker axis and the rotary axis of the gimbals are perpendicular to each other to easily drive the seeker. Accordingly, the rate sensor is mounted separate from the center of the rotary axis of the gimbals. This arrangement creates certain problems which include the requirement for a large space for equipment on the gimbals, the generation of mass unbalance around the rotary axis of the gimbals, the addition of a counterbalance weight required to compensate for the mass unbalance and an increase in inertial moment around the rotary axis caused thereby.